App size, remove the status bar CGRect r = [UIScreen mainScreen]. applicationFrame; this size will not change the width and height as the screen rotates, but after the screen rotates, it will automatically modify the width and height to lose the status bar height. Portrait screen (4-inch): x = 0, y = 20, width = 320, height = 548 horizontal screen (4-inch): x = 0, y = 0, width = 300, height = 568 screen size CGRect rx = [UIScreen mainScreen]. bounds; (4-inch) rx = x = 0, y = 0, width = 320, height = 568 fixed size, unchanged status bar size CGRect rect; rect = [[UIApplication sharedApplication] statusBarFrame]; always vertically. Portrait screen (4-inch): x = 0, y = 0, width = 320, height = 20 horizontal screen (4-inch): x = 300, y = 0, width = 20, height = 568 method for obtaining screen resolution in iphone CGRect rect = [[UIScreen mainScreen] bounds]; CGSize size = rect. size; CGFloat width = size. width; CGFloat height = size. height; in addition, pay attention to the minimum touch area when designing the UI. There are two arguments: 44*44. It seems to be from sdk 64*64. It is from standford handouts.